S-p-toluylmercapturic acid in the urine of workers exposed to toluene: a new biomarker for toluene exposure.
A mercapturic acid attached to the aromatic ring of toluene was for the first time detected in human urine as a metabolite of toluene. Since the metabolism of toluene is usually considered to take place at the side-chain, this gives, besides the biosynthesis of cresols, a further hint of a metabolic conversion of the aromatic system. We examined a group of 33 workers occupationally exposed to toluene, determining the concentrations of toluene in ambient air and in whole blood, o-cresol and hippuric acid in urine and p-toluylmercapturic acid (p-TMA) in urine. All blood and urine samples were collected post-shift. The renal excretion of S-p-toluylmercapturic acid showed highly significant correlations with established parameters of a biological monitoring of toluene. The median ambient air concentration was 63 ppm, ranging from 13 to 151 ppm, the median concentration of toluene in whole blood was 804 microg/l, corresponding to median urinary concentrations for o-cresol of 2.3 mg/l, hippuric acid of 2.3 g/l and p-TMA of 20.4 microg/l. p-TMA was not detectable in urine samples of a control group of 10 non-exposed persons. Both the German Biological Tolerance Values (BAT-values) for toluene in blood (1000 microg/l) and o-cresol in urine (3 mg/l) correspond to a mean p-TMA elimination of approximately 50 microg/l, and thus are in agreement with each other. According to our results p-TMA reflects internal toluene exposure diagnostically sensitive and specifical. With the developed analytical procedure we determined a median benzylmercapturic acid (BMA) concentration of 190 microg/l in the urine samples of the toluene exposed persons. We also determined a median BMA concentration of 30 microg/l in the control samples of non-exposed persons. However, these results are preliminary and require further confirmation as the reliability of the method was determined only for p-TMA.
Angerer
J
J
Friedrich-Alexander-University of Erlangen-Nürnberg, Institute and Clinic of Occupational-, Social- and Environmental Medicine, Erlangen, Germany.
Schildbach
M
M
Krämer
A
A
D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000652:urine; D000395:Air Pollutants, Occupational / Q000378:metabolism*; D015415:Biomarkers / Q000097:blood / Q000652:urine; D015331:Cohort Studies; D003408:Cresols / Q000652:urine; D004784:Environmental Monitoring / Q000379:methods; D008401:Gas Chromatography-Mass Spectrometry; D005858:Germany; D006626:Hippurates / Q000652:urine; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D014050:Toluene / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism* / Q000652:urine
D000395:Air Pollutants, Occupational; D015415:Biomarkers; D003408:Cresols; D006626:Hippurates; C110819:S-4-toluylmercapturic acid; D014050:Toluene; C030514:hippuric acid; D000111:Acetylcysteine; C034047:2-cresol